The present invention generally relates to devices for securing data discs and other record discs in releasable fashion, and in particular to a chuck for releasably securing a disc for high speed rotation during manufacturing and testing.
With the recent surge in sales of home computers and the increasing computerization of business and industry, data storage discs have become ubiquitous. Floppy discs, hard discs, CD ROM discs, magneto-optical discs, and the like have become very familiar to the general public, and their usage is measured in billions of discs per year. Due to the enormous numbers of data discs that are processed, it is essential that automated manufacturing equipment be employed to a maximum extent, so that costs may be held to a minimum. In the manufacture of these data discs, there are many process steps in which each disc must be releasably mounted on a rotatable arbor. Such process steps may include application of surface coatings, as well as cleaning, polishing, burnishing, and testing.
There are known in the prior art various forms of rotating disc chucks for releasably mounting a disc during an automated manufacturing process step. Due to the fact that data discs must conform to extremely close tolerances for planarity, surface finish, and coating integrity, the chuck securing a disc during processing must grip the disc with a high degree of centration, and cannot impart any curvature to the disc. Moreover, the chuck must grip the disc only at portions that will not be used for data recording.
One exemplary form of rotating disc chuck known in the prior art is described in U.S. Pat. No. 5,025,340, issued Jun. 18, 1991 to the present inventor. It employs an elastomeric bushing having a truncated conical configuration mounted coaxially on the outer end of the chuck, with an internal pneumatic piston coupled to the bushing. The periphery of the bushing is expanded against an annular land to hold a data disc adjacent to the edge of the central hole therein, and the piston is operated to drive the bushing in the axial direction and release the disc.